My best wrong answer is that there were different colored pixels for different front-end versions, and the app had some radically different responses depending

My best wrong answer is that there were different colored pixels for different front-end versions, and the app had some radically different responses depending on the version. Maybe MENA would return white, SE Asia green, people who signed up during a sale would return blue, whatever. After a while, the other pixels were removed and only one shade of purple were used for everyone, but the code for processing them was not removed. So now, if the tracking pixel is not a precise shade of purple, some unexpected shenanigans ensue.